use systemd.tmpfiles to manage folder permissions

services/immich.nix

@@ -16,6 +16,10 @@
     };
   };
 
+  systemd.tmpfiles.rules = [
+    "d ${config.services.immich.mediaLocation} 0755 ${config.services.immich.user} ${config.services.immich.group}"
+  ];
+
   environment.systemPackages = with pkgs; [
     immich-go
   ];